Tuning configuration

buf-cache-size specifies the overall size of Liberator’s buffer cache in megabytes.

Syntax: buf-cache-size <size-in-megabytes>

Type: integer

Default value: 16 megabytes

buf-elem-len specifies the length of of a standard buffer element, in bytes. Increasing this improves performance if using very large messages, but it will considerably affect memory usage.

Syntax: buf-elem-len <length-in-bytes>

Type: integer

Default value: 4096 bytes

container-yield-size specifies the maximum number of records that can be served from a container before the operation yields possession of the session thread and is moved to the back of the session thread’s work queue. Serving containers in batches of rows prevents the serving of a large container from delaying the processing of other operations in a session thread’s queue. This increases the perceived responsiveness of a client application, at the expense of a small overhead in switching between operations.

Since: Liberator 7

Syntax: container-yield-size <size-in-entries>

Type: integer

Default value: 100

Values accepted: 1–n (where n is the maximum value of an integer on the platform)

disable-monitoring is used to disable specific types of Liberator monitoring. It can be used to disable a combination of object, session, and listener (subscription) monitoring.

If you disable object or session monitoring (or both), listener monitoring is also disabled.

Syntax: disable-monitoring <option>[|…​]

Type: string

Default value: none

Examples:

json-yield-size is the maximum number of bytes of a JSON message (a chunk) that can be added to an outbound queue in one go before the operation yields possession of the session thread and is moved to the back of the session thread’s work queue. Serving JSON messages in chunks prevents the serving of a large JSON object from delaying the processing of other operations in a session thread’s queue. This increases the perceived responsiveness of a client application, at the expense of a small overhead in switching between operations.

Since: Liberator 7.1.8

Syntax: json-yield-size <size-in-bytes>

Type: integer

Valid values: 80 to 2147483647

Default value:

json-yield-retry-time is the amount of time in seconds to back off after yielding.

Since: Liberator 7.1.8

Syntax: json-yield-retry-time <time-in-seconds>

Type: integer

Default value: 0.01

object-hash-size specifies the size of the hashtable that Liberator uses to manage its objects. Increasing this item makes Liberator use extra memory, but it speeds up updates and requests if the value is high enough to ensure there aren’t too many hash collisions.

In addition to requested objects, Liberator allocates an internal object for each client session. So, at a minimum, set object-hash-size to: max_num_objects + max_concurrent_users.

We recommend that you set object-hash-size to twice the maximum number of objects that Liberator is likely to handle.

Syntax: object-hash-size <size-in-table-entries>

Type: integer

Default value: 16384

output-queue-size specifies the number of update messages the Liberator stores per client. The main use for this item is when a client loses its connection to Liberator; while the connection is down, Liberator stores updates that are received for the client’s subscriptions and sends them to the client when the connection is re-established.

Syntax: output-queue-size <size-in-messages>

Type: integer

Default value: 64 messages

Values accepted: Maximum 4096 messages

response-batch-size specifies the maximum size in bytes of RTTP response messages. It only applies when the StreamLink connection type is "Streaming JavaScript via IFrame" ("type 5" connections).

Syntax: response-batch-size <size-in-bytes>

Type: integer

Default value: 0 (no maximum size is set)

system-max-files specifies the maximum number of file descriptors that Liberator’s process may create. Liberator requires file descriptors for user sessions, log files, connections with DataSource peers, and HTTP requests.

On start up, Liberator adjusts the file descriptor limit for its process to system-max-files, or the licensed number of users plus a margin of 512, whichever is the greater of the two values. If Liberator is licensed for an unlimited number of users, only the value of system-max-files is used.

On a Liberator licensed for an unlimited number of users, set system-max-files to the expected number of users plus a margin of 512.

If Liberator is started as an unprivileged user, it cannot set a file descriptor limit greater than the user’s hard limit (the output of ulimit -H -n). In Red Hat Enterprise Linux 7, the default user hard-limit for open file descriptors is 4096. If Liberator fails to set a file descriptor limit, it writes NOTIFY: Failed to set system-max-files to value to the event log, and retries with successively lower values until it succeeds, halving the value with each attempt.

To avoid the restriction of the user hard-limit for file descriptors, use one of the options below:

Syntax: system-max-files <max-number>

Type: integer

Default value: 1024

threads-num specifies the number of client threads (session threads) that Liberator should use to serve RTTP clients.

When the contention between threads for CPU cores is low, increasing the number of Liberator’s session threads can increase the number of clients Liberator can service.

For Liberator deployments managed by the Deployment Framework, don’t edit the threads-num configuration item directly. Instead, edit the LIBERATOR${THIS_LEG}_THREADS_NUM configuration variable in the Deployment Framework file global_config/environment.conf.

If you assign threads-num a value outside the range of valid values, then Liberator logs a warning to the console and to the event log, and reduces the number of client threads to 1.

Liberator also uses additional threads for DataSource peer connections. See How can I…​ Configure threads for peer communication.

Syntax: threads-num <max-number>

Type: integer

Default value: 1

Values accepted:

thread-queue-notify-always is a boolean item that, when set to TRUE, causes Liberator to record the size of Liberator’s threads queue in the event log every thread-queue-notify-period seconds.

Alternatively, you can just configure Liberator to log the size of the threads queue when it exceeds a given size – see thread-queue-notify-levels.

An event log entry about the threads queue, typically looks like this:

Syntax: thread-queue-notify-always <boolean>

Type: boolean

Default value: FALSE (no time-based logging of the threads queue)

For more about the event log, see Liberator logging.

thread-queue-notify-levels specifies an array of queue sizes at which Liberator logs information about the size of Liberator’s threads queue to the event log.

For example:

With the above configuration, Liberator reports the initial size of the threads queue, and if the size subsequently exceeds 10 entries, it logs the size. If after this, the queue size exceeds 100 entries, it logs the size again.

Alternatively, you can just configure Liberator to log the size of the threads queue at regular intervals by setting thread-queue-notify-always and thread-queue-notify-period.

If you specify thread-queue-notify-levels together with thread-queue-notify-always and thread-queue-notify-period, Liberator first logs the queue size when it exceeds the first level in thread-queue-notify-levels, and then writes log entries every thread-queue-notify-period.

Syntax: thread-queue-notify-levels level-1 level-2 level-3 …​

Type: integer

Default value: 10000 100000 1000000

For more about the event log, see Liberator logging.

thread-queue-notify-period specifies the interval at which Liberator records the size of Liberator’s threads queue in the event log when thread-queue-notify-always is TRUE.

Syntax: thread-queue-notify-period <interval-in-seconds>

Type: float

Default value: 0 seconds (timer is disabled)

For more about the event log, see Liberator logging.

user-hash-size specifies the size of the user hashtable for authorizing users who log in to Liberator.

Syntax: user-hash-size <size-in-table-entries>

Type: integer

Default value: 8192 entries

See also: